6.3 Non-Ischemic Stress Echo and Hemodynamic Provocation

Start with the physiologic question

CCI task B9 is to perform non-ischemic stress echocardiography. Unlike a standard ischemia study centered on regional wall motion, this examination may ask why exertional dyspnea occurs, whether an LV outflow tract (LVOT) gradient is provocable, whether a valve gradient or regurgitant lesion becomes important with flow, whether pulmonary pressure rises with symptoms, or whether a ventricle has contractile reserve. The team cannot acquire every possible variable at peak. Before stress, confirm the ordered question, stressor, stages, priority measurements, termination plan, and who supervises each maneuver.

Exercise is the preferred stressor for many non-ischemic questions because symptoms and hemodynamics occur under physiologic load. Supine or semi-supine bicycle exercise is especially useful because Doppler can be acquired at baseline, low workload, peak, and recovery. Treadmill testing may be appropriate, but transient Doppler findings can fade during transfer. Dobutamine is useful for selected contractile- or flow-reserve questions, including some low-flow valve evaluations; it is not a physiologic replacement for every exercise question. The supervising clinician chooses the stressor.

Diastolic and pulmonary hemodynamic stress

The 2025 ASE diastolic guideline recommends diastolic exercise echocardiography in selected symptomatic patients when estimated left-atrial pressure is normal at rest but HFpEF remains suspected. Acquire an excellent apical four-chamber view before exercise and retain mitral E and A, septal and lateral tissue Doppler e-prime as ordered, TR peak velocity, and stage-specific HR and BP. During bicycle stress, collect priority Doppler at lower workloads before E and A fuse; repeat at recovery if peak tachycardia prevents measurement. A ratio or velocity is not interpretable when the sample volume moved, the envelope is incomplete, or different beats and stages are mixed.

A rise in TR velocity during exercise reflects both flow and pressure and must be considered with age, workload, right-heart response, and signal quality. Current right-heart guidance cautions against treating one exercise pulmonary-pressure number as universally abnormal. Trace only a complete, well-aligned envelope and document when no reliable signal exists. Do not inject an enhancing agent for a weak TR signal or change oxygen solely to obtain a number unless an authorized protocol specifically directs it. Symptoms, workload, BP, and oxygen saturation when ordered remain part of the physiologic story.

Dynamic obstruction and valve provocation

For hypertrophic cardiomyopathy, provocation can include Valsalva, standing, squat-to-stand, or exercise. These maneuvers change preload and afterload differently. Obtain resting anatomy, color localization, and LVOT PW mapping before CW. During each ordered maneuver, align through the LVOT and label the exact position and stage. A dynamic LVOT envelope often peaks late in systole. Mitral-regurgitation velocity may be higher, begin earlier, and contaminate the same CW line; use color direction, PW mapping, waveform timing, multiple windows, and audible/visual signal characteristics to separate them. Tracing MR as LVOT can grossly overstate the gradient.

Exercise is the physiologic method to provoke latent LVOTO; the 2022 ASE multimodality HCM guideline does not recommend dobutamine for this purpose because it can create dynamic gradients even in people without HCM. The sonographer must not improvise a Valsalva, dehydration, medication change, or more forceful maneuver. Confirm that the clinician wants the maneuver, coach it consistently, and stop coaching if symptoms or instability develops. The supervising clinician determines whether a gradient is meaningful and whether testing should continue.

Valve stress likewise requires matched data. A mitral-stenosis study may prioritize transmitral mean gradient and TR velocity at baseline, low workload, and peak. A prosthetic-valve study may compare gradients and effective flow response. In low-flow, low-gradient aortic stenosis, low-dose dobutamine may assess flow reserve and changing valve hemodynamics. Keep PW sample level, CW window, gain, sweep speed, averaging method, and stage labels consistent; never compare a rest apical envelope with a peak right-parasternal envelope without identifying the change. Interpretation uses the full disease-specific guideline, not an isolated peak gradient.

Safety and handoff

Non-ischemic does not mean low risk. Severe dyspnea, chest pain, presyncope, hypotension, extreme hypertension, sustained arrhythmia, desaturation, a rapidly rising gradient with symptoms, or right-ventricular deterioration requires immediate communication. The sonographer reports observable facts and captures supporting data only if doing so does not delay care. The authorized clinician decides termination and treatment; an immediate threat triggers the emergency response.

At completion, verify that every saved loop and Doppler envelope names the stage, workload or maneuver, position, HR, BP, rhythm, and relevant symptoms. Report incomplete targets rather than filling gaps with a later stage. A focused, reproducible dataset answers the question better than an impressive collection of unlabeled peak signals.